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Cell Phone-based Optometry Solution
The Inverse of Shack-Hartmann
Vitor Pamplonaeyenetra.com
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Andres Rueda
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Thermometer for vision
Collaboration with: Ankit Mohan , Manuel M. Oliveira, Ramesh Raskar
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Collaboration with: Ankit Mohan , Manuel M. Oliveira, Ramesh Raskar
Thermometer for vision
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6.5 Billion
people
4.5B have a
cell phone
2B have
refractive errors
0.6B have URE
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Shack-Hartmann Wavefront Sensor
Expensive; Bulky, Requires trained professionals
Wavefront aberrometer
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Shack-Hartmann Wavefront Sensor
Laser
Sensor MicrolensArray
Planar Wavefront
Spot Diagram
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Laser
Sensor
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Displacement = Local Slope
of the Wavefront
Spot Diagram
Shack-Hartmann Wavefront Sensor
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NETRA = Inverse of Shack-Hartmann
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Spot Diagram on LCD
Cell Phone Display
Eye Piece
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Spot Diagram on LCD
Inverse of Shack-HartmannUser interactively creates the Spot Diagram
Displace 25 points but 3 parameters
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Spot Diagram on LCD
Inverse of Shack-HartmannUser interactively creates the Spot Diagram
Displace 25 points but 3 parameters
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Eye
Relaxed Eye with Myopia
Blurred point
Red pointat infinity
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
12
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Eye
Relaxed Eye with Myopia
Distinctimage points
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
Pinholes
13
Red pointat infinity
Scheiner’s Principle
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Eye
Relaxed Eye with Myopia
Virtual red pointat infinity
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
14
A
B
Distinctimage points
Display
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Relaxed Eye with Myopia
A
B
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
Virtual red pointat finite distance
Move spots towards each
other
Display
Eye
15
Distinctimage points
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B
A
Points overlap
Relaxed Eye with Myopia
Display
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
Eye
Virtual red pointat finite distance
Move spots towards each
other
16
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B
A
Points overlap
Relaxed Eye with Myopia
Display
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
Eye
Virtual red pointat finite distance
Move spots towards each
other
17
d
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Points overlap
Relaxed Eye with Myopia
perfect vision
myopia
hyperopia
~10cminfinity
Focusing Range
Eye
18
d
d
1
Point at infinity
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Interactive Method
20
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Interactive Method
21
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Interactive Method
22
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Interactive Method
23
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Interactive Method
Farthest Focal Point(myopia, hyperopia, astigmatism) 24
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Limitations
• Children
• Ability to align lines
• Resolution is a function of the display DPI
– Samsung Behold II – 160 DPI – 0.35D
– Google Nexus One – 250 DPI – 0.2D
– Apple iPhone 4G – 326 DPI – 0.14D
25
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Why Now?
0.35um
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Confidential 27
NETRA Prototypes Worldwide29 partners in 14 countries.
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Clinical Testing Partners
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NETRA Team at LVPEI, India
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Kenya
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Tufts U. (Boston) NETRA vs Manifest Refraction
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
4.00
5.00
-5.00 -3.00 -1.00 1.00 3.00 5.00
Net
ra (D
)
Retinoscopy (D)
13 adults
-7.00
-5.00
-3.00
-1.00
1.00
3.00
5.00
7.00
-7.00 -2.00 3.00
Net
ra (D
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Retinoscopy (D)
29 adults
LVPEI (India)NETRA vs Retinoscopy
Validation: Side by Side Trials
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Preventable Blindness
WHO 2004
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Unique, quantitative lens mapping
CATRA: Quantitative Cataract Maps
with: Erick Passos, Jan Zizka, Everett Lawson, Esteban Clua , Manuel M. Oliveira, Ramesh Raskar
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Testing the Presence of Cataracts
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Blin
kin
g p
atte
rns
on
Scr
ee
n
Cell Phone Display
Pinhole
Lens
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36 years old female with Posterior Sub-Capsular (10%)
CATRA’s Opacity MapSlit-lamp
Retro-illumination
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For the Future
• Ophthalmology for Masses– >.5 billion URE. > 2.5 billion RE. -> Devices for all
• Quality of phones (resolution) will increase exponentially
• New features (recently cataracts, next Retinal NETRA)
• Smart phones will take over the market in developing world countries like India in next 5 years.
• Hardware store
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NETRAhttp://eyenetra.com
Vitor Pamplona
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Photography in 1960s
Illana Tamir
Roboppy
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Today, cameras are everywhere
Photo: Derek K. Miller
Photo: Tyler
Photo: John Kannenberg
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Corneal TopographerWavefront Aberrometer
Phoropter
Optometry Today
Snellen chartTrial set of lenses Lasers
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“point-and-shoot” optometry
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Traditional User Driven
Mass-use Devices Scientific Instruments
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Phoropter
Snellen chart
Trial lenses
Reading Charts
• Accuracy– Sharpness Estimation is subjective
– Brightness affects results
– Pupil size variation and DoF
• Cost– Trial Lens Set > $150
– Bulky
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EHR
DeliveryDiagnosticEyecare
Providers
New Ecosystem
Asynchronous
Medical IT Systems
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Retinoscope w/
Lenses
Auto-refracto-
meter
Chart with
Lenses
In-Focus: Focometer Optiopia
Solo-health: EyeSite
NETRA
Technology Shining Light plus lenses
FundusCamera
Moving lenses + target
Moving lenses + target
Reading chart on monitor
Cellphone+ eyepiece
Cost to buy $2,000* ~$10,000 ~$100 ~$495 ~$200 -- $30
Cost per test ~$36 ~$36 ~$5 -- -- -- ~$1
Data capture No Comp. No No No Comp. Phone
Mobility 10Kg 2kg 1kg 10Kg
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Human Eye
Human Eye
Cornea(~40D) Crystalline lens
(10~20D)
Retina
46
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Human Eye
Human Eye
Cornea(~40D) Crystalline lens
(10~20D)
Retina
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Accommodation
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Infinity
Perfect Vision System
Human Eye
Infinity
Subject can focusat infinity
10cm
Normal Vision
48
Accommodation Range
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Myopia (nearsightedness)
Infinity
Subject cannot focusat far distances
10cm
Normal Vision
Myopia
Wrong focal point
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Accommodation Range
Infinity
Human Eye
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Myopia Correction
Infinity
Subject can focusat infinity
10cm
Normal Vision
Myopia
Divergent Lens
Corrected Myopia
50
Accommodation Range
Infinity
Human Eye
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Hyperopia (farsightedness)
Infinity 10cm
Normal Vision
Myopia
Hyperopia
Wrong focal point
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Accommodation Range
Infinity
Human Eye
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Hyperopia Correction
Infinity
Accommodation Range
10cm
Normal Vision
Myopia
Hyperopia
Convergent Lens
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Corrected Hyperopia
Infinity
Human Eye
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Refractive Errors and Shifted Range
Perfect vision
Myopia
Hyperopia
10cmInfinity
Need to measure
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1m 33cm Distance
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Refractive Errors and Shifted Range
Perfect vision
Myopia
Hyperopia
10cmInfinity
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-10D0D
Diopter = 1/Distance
-3D-1D
1m 33cm
+1D+3D
Distance
Diopter
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Astigmatism: angle-dependent refractive error
http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html 56
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Astigmatism: angle-dependent refractive error
http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html 57
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Astigmatism: angle-dependent refractive error
http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html 58
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Refractive Power as a Function of Angle
59
Cylinder SphereAxis Cyl.Unknowns:
SCP )(sin(2
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Astigmatism
Cross or points may never meet with a 1d search !60
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Astigmatism
Lines reduce the problem to a 1d search61
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Measuring the Accommodation Range
62
Perfect vision
~10cmInfinity
Myopia
Hyperopia
Step 1: Far limit Step 2: Near limit
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Measuring the Accommodation Range
63
Perfect vision
~10cmInfinity
Myopia
Hyperopia
Step 1: Far limit Step 2: Near limit
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Measuring the Accommodation Range
64
Perfect vision
~10cmInfinity
Myopia
Hyperopia
Step 1: Far limit Step 2: Near limit
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Points overlap
A
B
Display
Virtual Point at the far limit
Relaxed Eye
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Points overlap
A
B
Display
Accommodated Eye
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Virtual pointgetting closer
Move points towardseach other
Subject Accommodates to fix the “blur”
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Points overlap
A
B
Display
Accommodated Eye
67
Virtual pointgetting closer
Move points towardseach other
Subject Accommodates to fix the “blur”
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Points overlap
A
B
Display
Accommodated Eye
68
Virtual pointgetting closer
Move points towardseach other
Subject cannot accommodate more than the previous point
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Patterns for Alignment Task
Displayed
Subject view
Displayed
Subject view
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Visual Cryptography
A B A B A B A B A B
A B A B A B A B A B
[NaorShamir94]
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Patterns for Alignment Task
Displayed
Subject view
Displayed
Subject view
70
Visual Cryptography
A B A B A B A B
A B A B A B A B A B
A B
[NaorShamir94]
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Summary of Interaction
Farthest Point(myopia, hyperopia, astigmatism)
Nearest Point(presbyopia)
Accommodation Range
71